After 11 years in the hot seat on budget day, Gordon Brown will be the warm-up act as he takes prime minister's questions before the chancellor, Alistair Darling, stands up to unveil the much anticipated contents of his first budget.

11.30am

Brown is likely to be taken to task over the spiralling cost of military operations in Iraq and Afghanistan, which has almost doubled to more than £3bn this year. Figures published earlier this week by the Commons defence committee showed operations by British forces in Afghanistan had soared to more than £1.6bn, a rise of 122%, and to £1.6bn in Iraq, a rise of 72%.

The costs are about 50% more than the government forecast just three months ago. The prime minister also faces tough questions about the return of British troops from Iraq, after military officials made it clear that regardless of Brown's pledge last October, the number of troops in Iraq will not now be cut in spring.

Brown, who is committed to boosting home ownership, faces questions on the state of the housing market following a survey by the Royal Institution of Chartered Surveyors published earlier this week, which reveals that market conditions are the worst for more than a decade.

The prime minister could be in for a ribbing over his government's citizenship plans, which envisage children swearing allegiance to the Queen - a proposal which sparked an uproar after being unveiled by former attorney general Lord Goldsmith yesterday as part of measures to restore a sense of British pride and belonging.

Brown could also be put on the spot on whether he intends to deliver on a pledge to change the attorney general's powers. Brown said last July that the role, which combines legal and ministerial functions, "needed to change", following controversy over the way the Goldsmith became drawn into the BAE prosecution, the cash for honours inquiry and the legal advice on going to war in Iraq.

But not all of his ministers are convinced - including the current attorney general, Lady Scotland, who is believed to want to retain the power in the draft constitutional reform bill, due to be published shortly. Will Brown stand by his guns?

As soon as he sits down at 12.30pm, his chancellor will rise to announce his budget. Follow all the budget coverage at guardian.co.uk/politics.

Midday

Economy

Brown rises and off we go. First question is on the economy. Michael Foster (Lab, Hastings and Rye) raises measures such as the minimum wage that have helped tackle child poverty.

Foster asks Brown for other measures in place. Brown rolls off the 12 million children benefiting from child benefit and tax credits, the three million back in employment.

We will do more in the next few years, he says, but it wouldn't be possible to reduce it further if you went along with tax cuts, he says in a nod to the Tories.

David Cameron

Cameron gets up to quip that planted questions don't seem to be getting any better.

On to international efforts in Darfur. On any objective measure, the situation on the ground for those facing famine in Darfur isn't getting any better, he says.

Brown says there should be sanctions against the Sudanese government, that the African governments must make their contributions, but that everyone should get around the table to sort this crisis out.

12.05pm

Cameron says that Brown said he would visit Darfur. What steps is he taking to support the challenges faced by Darfur?

Brown says the way forward is to move to peace talks as quickly as possible and that rebel groups need to come to the table.

Cameron says a no-fly zone is vital. Anyone who has been to Darfur will talk to people in camps who say it was the Sudanese army that drove me out of my village and they arrived in an aircraft.

So, is Brown still in favour of a no-fly zone?

Brown says he would like to move ahead if at all possible but the area they would have to police is the size of France.

We can get progress on that and get people to the peace talks.

Northern Ireland

Eddie McGrady (SDLP, South Down) calls on Brown to commit to complete devolution for Northern Ireland - including on policing, as well as investment - is needed.

Brown says there is great progress in Northern Ireland, and it's great the Queen is paying a visit, and he hopes that all parties will look at the proposals in Northern Ireland on policing and move forward on that too.

12.10pm

Nick Clegg

The Liberal Democrat leader says it is important to get rich people out of British politics.

The British public is looking on disgusted at the refusal of the Tories and Labour to entertain real reform of electoral funding.

Brown agrees there should be changes on electoral funding, and he adds there should be greater transparency on MPs' spending.

Clegg says Brown isn't doing anything.

Brown says he is slightly frustrated that Clegg didn't take in what he just said - ie that he pretty much agreed with him on all fronts.

Budget

Andrew MacKay (Con, Bracknell) asks whether Alistair Darling has been more cooperative with Brown as PM in filling him in about his budget than Brown was when he was Blair's chancellor.

Brown dismisses the claim he used to give Blair just two days' notice.

Free votes

David Cameron comes back in. He raises the issue of free votes on matters of conscience, such as the human fertilisation and embryology bill.

The issue has been whipped by Labour in the House of Lords, but it now seems Labour ministers who are uncomfortable with the bill may be able to abstain, he says.

Cameron says the vote should never have been whipped. What is Brown going to do next, he asks.

Brown says his government will make its decision (for Labour MPs) when the bill comes to the Commons.

12.15pm

Cameron is trying to get Brown to say whether he has changed his mind and whether his MPs will now be entitled to a free vote.

Brown says Cameron simply doesn't understand how this bill came about, but, by the way, he will respect the conscience of his MPs over this issue.

Will he talk to managers about ways to avoid danger at sea? Brown says he's saddened about the strike and all efforts need to be taken to ensure the service continues uninterrupted.

12.20pm

Military

Bob Russell raises support for military personnel wearing their uniforms in public.

Shouldn't the government make it an offence if someone is assaulted while wearing the uniform?

Brown says the police already have powers to deal with people who abuse our armed forces and the public is on side on soldiers receiving the recognition and the acclaim they deserve.

Back to Sudan and UK humanitarian aid funding. Brown says britain stands ready to give additional money if those peace talks are forthcoming.

London

Boris Johnson gets up, rather flustered over a question earlier about buses in London which suggested that if he won the mayoral election bus services would suffer.

Misrepresented again, blusters Johnson.

He then gets into a row with Brown over his mayoral pledge for policing.

Brown quotes him as saying that there are cuts to be found in the Metropolitan police - though outside the chamber Johnson has already argued his words have been twisted and that he intends to have more police on the streets, and on public transport.

Homes

Tom Brake (Lib Dem, Carshalton and Wallington) asks about a convoluted ruling to do with decent homes funding - money to upgrade social housing which will affect tenants in his area. Will Brown meet tenants?

Brown rolls off government policy but doesn't agree to that cup of tea and chat.

Another Labour question, giving Brown the opportunity to talk about the government's climate change commitments.

And again, this time from Fiona McTaggart on employment and skills.

Can the government do more to get employers to commit to giving more skills to our young people?

Brown says McTaggart is absolutely right, this is important and that's why the government is doing more than ever to provide young people with those skills.

A question on Northern Ireland by Jeffrey Donaldson is followed by one on flooding from Jamie Reed (Lab, Copeland). How to prevent it?

Brown says more funding is on the pipeline.

Brown is taken to task about the foot and mouth disease crisis last summer and insists the government is taking on board the recommendations in the Anderson report.

He is then asked about forced marriages in Britain after it emerged that around 3,000 women a year are subjected to forced marriages.

Brown denounces these cases as "intolerable" and vows to clamp down on abuses. That's it for Brown - over to Darling for his first budget.